To efficiently compress and transmit an audio signal, part of a frequency band of the audio signal may be removed. A format for compressing audio data may be a moving picture experts group (MPEG)-1 audio layer 3 (MP3), advanced audio coding (ACC), window media audio (WMA), or the like. An audio codec may include a specified frequency for removing part of a frequency band of an audio signal when compressing the audio signal.
If part of a frequency band of an audio signal is lost, the audio signal may deteriorate in sound quality and may be changed in timbre. Thus, when an audio signal, a partial frequency band of which is lost, is played back, the lost frequency band of the audio signal may be recovered to enhance sound quality and timbre.
If compression information is included in an audio signal, a lost frequency band of the audio signal may be recovered according to a criterion of the compression information. If the compression information is not included in the audio signal, the lost frequency band may be recovered by analyzing a spectrum of the audio signal.